AFTERTREATMENT DEVICE NOX CONVERSION EFFICIENCY DIAGNOSTICS USING ON BOARD ADAPTIVE DIAGNOSTIC ALGORITHM

• US 20100043400A1
• Filed: 08/07/2009
• Published: 02/25/2010
• Est. Priority Date: 08/19/2008
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Wang, Yue-Yun, Solbrig, Charles E., Yanakiev, Ognyan N.
• Granted Patent: US 8,201,444 B2
• Time in Patent Office: Days
• US Class Current: 60/276
• CPC Class Codes: F01N 11/002 the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
• CPC Class Codes: F01N 2550/03 of sorbing activity of adsorbents or absorbents
• CPC Class Codes: F01N 2560/026 for measuring or detecting NOx
• CPC Class Codes: F01N 2560/06 the means being a temperature sensor
• CPC Class Codes: F01N 2570/18 Ammonia
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A powertrain includes an internal combustion engine and an aftertreatment system having an aftertreatment device utilizing a catalyst to convert NOx. A method for indicating a malfunctioning catalyst includes monitoring an actual NOx content exiting the aftertreatment system, monitoring factors affecting conversion efficiency of the aftertreatment device, determining a predicted threshold NOx content exiting the aftertreatment system for an exemplary malfunctioning catalyst based upon the factors affecting conversion efficiency, comparing the actual NOx content exiting the aftertreatment system to the predicted threshold NOx content exiting the aftertreatment system, and indicating a malfunctioning catalyst based upon the comparing.

Claims

1. Method for indicating a malfunctioning catalyst in a powertrain including an internal combustion engine and an aftertreatment system having an aftertreatment device utilizing a catalyst to convert NOx, the method comprising:

monitoring an actual NOx content exiting the aftertreatment system;

monitoring factors affecting conversion efficiency of the aftertreatment device;

determining a predicted threshold NOx content exiting the aftertreatment system for an exemplary malfunctioning catalyst based upon the factors affecting conversion efficiency;

comparing the actual NOx content exiting the aftertreatment system to the predicted threshold NOx content exiting the aftertreatment system; and

indicating a malfunctioning catalyst based upon the comparing.

2. The method of claim 1, wherein monitoring the factors affecting conversion efficiency comprises:

monitoring a NOx content entering the aftertreatment system;

monitoring a bed temperature within the aftertreatment device;

monitoring a space velocity within the aftertreatment device; and

monitoring an amount of ammonia storage within the aftertreatment device.

3. The method of claim 2, wherein monitoring the NOx content entering the aftertreatment system comprises operating a virtual NOx sensor.

4. The method of claim 1, wherein monitoring the actual NOx content exiting the aftertreatment system comprises:

monitoring a NOx sensor located downstream of the aftertreatment system; and

determining the actual NOx content exiting the aftertreatment system based upon integrating data from the monitored NOx sensor located downstream of the aftertreatment system through a time period; and

wherein determining the predicted threshold NOx content exiting the aftertreatment system for the exemplary malfunctioning catalyst comprises

determining an instantaneous predicted threshold NOx content exiting the aftertreatment system based upon the factors affecting conversion efficiency, and

determining the predicted threshold NOx content exiting the aftertreatment system based upon integrating instantaneous predicted threshold NOx content exiting the aftertreatment system through the time period.

5. The method of claim 1, wherein determining the predicted threshold NOx content exiting the aftertreatment system for the exemplary malfunctioning catalyst comprises utilizing a look-up table.

6. The method of claim 1, wherein determining the predicted threshold NOx content exiting the aftertreatment system for the exemplary malfunctioning catalyst comprises calculating the predicted threshold NOx content exiting the aftertreatment system for the exemplary malfunctioning catalyst with a programmed functional relationship.

7. The method of claim 6, wherein calculating the predicted threshold NOx content exiting the aftertreatment system for the exemplary malfunctioning catalyst with the programmed functional relationship comprises:

determining a predicted nominal NOx content exiting the aftertreatment system for an exemplary fresh catalyst based upon the factors affecting conversion efficiency of the aftertreatment device; and

calculating the predicted threshold NOx content exiting the aftertreatment system for an exemplary malfunctioning catalyst by dividing the predicted nominal NOx content exiting the aftertreatment system for the exemplary fresh catalyst by a calibratable threshold factor.

8. The method of claim 7, wherein the calibratable threshold factor is based upon a space velocity within the aftertreatment device and a bed temperature within the aftertreatment device.

9. The method of claim 1, further comprising:

monitoring a NOx content entering the aftertreatment system; and

wherein determining the predicted threshold NOx content exiting the aftertreatment system for the exemplary malfunctioning catalyst comprises

determining a predicted conversion efficiency for the aftertreatment device based upon the factors affecting conversion efficiency of the aftertreatment device, and

determining the predicted threshold NOx content exiting the aftertreatment system for an exemplary malfunctioning catalyst based upon the predicted conversion efficiency and the monitored NOx content entering the aftertreatment system.

10. The method of claim 1, further comprising warning an operator of the powertrain based upon the indicating.

11. The method of claim 1, further comprising modulating operation of the powertrain based upon the indicating.

12. The method of claim 11, wherein modulating operation of the powertrain comprises commanding operation of the engine to create less NOx.

13. The method of claim 11, wherein modulating operation of the powertrain comprises operating the aftertreatment system assuming decreased performance from the malfunctioning catalyst.

14. Method for indicating a malfunctioning catalyst in a powertrain including an internal combustion engine and an aftertreatment system having an aftertreatment device utilizing a catalyst to convert NOx, the method comprising:

monitoring an actual NOx content exiting the aftertreatment system;

monitoring factors affecting conversion efficiency of the aftertreatment device;

determining a predicted nominal NOx content exiting the aftertreatment system for an exemplary fresh catalyst based upon the factors affecting conversion efficiency of the aftertreatment device;

comparing the actual NOx content exiting the aftertreatment system and the predicted nominal NOx content exiting the aftertreatment system for the exemplary fresh catalyst; and

indicating a malfunctioning catalyst if the actual NOx content exiting the aftertreatment system exceeds the predicted nominal NOx content exiting the aftertreatment system for the exemplary fresh catalyst by more than a threshold NOx content above nominal.

15. The method of claim 14, wherein the monitoring factors affecting conversion efficiency comprises:

monitoring a NOx content entering the aftertreatment system;

monitoring a bed temperature within the aftertreatment device;

monitoring a space velocity within the aftertreatment device; and

monitoring an amount of ammonia storage within the aftertreatment device.

16. System for indicating a malfunctioning catalyst in a powertrain including an internal combustion engine and an aftertreatment system having an aftertreatment device utilizing a catalyst to convert NOx, the system comprising:

the aftertreatment device;

a sensor located to detect NOx content present in an exhaust gas flow downstream of the aftertreatment device; and

a control module

monitoring the sensor located to detect NOx content present in an exhaust gas flow downstream of the aftertreatment device,

monitoring factors affecting conversion efficiency of the aftertreatment device,

determining a predicted threshold NOx content exiting the aftertreatment system for an exemplary malfunctioning catalyst based upon the factors affecting conversion efficiency,

comparing data from the sensor located to detect NOx content present in an exhaust gas flow downstream of the aftertreatment device to the predicted threshold NOx content exiting the aftertreatment system, and

indicating the malfunctioning catalyst based upon the comparing.

17. The system of claim 16, the control module further generating commands to change operation of the engine based upon the indication of the malfunctioning catalyst.

18. The system of claim 16, the control module further generating commands to change operation of the aftertreatment system based upon the indication of the malfunctioning catalyst.